James J. Coleman
February 1, 2008
Q: What is your area of expertise?
A: Semiconductor lasers—the optical component in fiber optics telecommunications systems [and] CD and DVD players. Semiconductor lasers are also used in industrial applications like high-precision laser welding, things like that. There are lasers all around us.
Q: Why did you become an electrical engineer?
A: I got a short-wave radio when I was 11 or 12 years old, a second-hand short-wave radio. It was broken, actually there were tubes burned out in it. Two things happened. One is, I managed to get it fixed by finding the replacement tubes. And the other was I turned it on and was just amazed that I could hear the BBC in London and Radio Prague and Radio Moscow and things like that. So the combination of that ability and this technical box of stuff just captured my attention and has ever since.
Q: Tell us about your career.
A: I came to the University of Illinois and received my bachelor’s, master’s, and PhD. Then I went to Bell Laboratories in New Jersey and worked on lasers for telecommunications systems. Then I went to Rockwell International in Southern California and worked on lasers for defense systems as well as solar cells and other kinds of photonic devices. And then I came back to Illinois and have worked here for many years doing research and development on semiconductor lasers.
Q: You’ve had a long affiliation with Illinois. Why?
A: I’m originally from Chicago. I knew a little bit about Illinois. Illinois offered me an excellent engineering school, although I didn’t realize how good the engineering school was at the time, for a price that a city boy could afford. It was quality and value that brought me to Illinois originally. And I suspect it still brings people here.
Q: Tell me about a research accomplishment you’re proud of.
A: We’ve had a lot of wonderful students come through the group and we’ve gotten a lot of stuff done. But if you asked me to pick the one thing that had the most impact, we made some critical contributions to a material structure called a “strained layer,” it’s part of a laser, in the late 80s and early 90s that has turned out to be a critical component of lasers, especially fiber optic laser systems. No one these days makes a long-distance call or uses their cell phone and doesn’t have part of that signal path include some work that originated here at Illinois.
Q: What role do students play in your research?
A: We have undergraduates who work in my lab all the time, one or two of them every semester, doing a senior project or an independent study. We don’t send them off and make them do little baby projects. They are assigned a graduate mentor and they do whatever we’re doing at the time. They can contribute. They’re bright young engineers. In another year or two they’re going to be graduate students. They’ve got some good background and ability, all they lack is experience. We show them more at the beginning, but by the end of the semester they’re carrying out work and learning at the same time.
You can’t do anything at a university like this without the graduate students. It’s very rare that a faculty member can work on his own. There have been students involved in everything we’ve done. The typical graduate student…in their first year or two, are very bright but inexperienced and all of the intellectual ideas come from me. By the end, they’re about ready to go out into industry be independent researchers. We’re just coworkers and colleagues. They produce as many ideas as I do or more. There’s a transition as they go through the program.
Q: What do you enjoy most about teaching?
A: If you are a research professor, basically, you spend half your time as a teacher and half your time as a researcher. And of course researching is really teaching because you’re working with students.
The material itself, once you’ve taught it once or twice you know it inside and out so you don’t really gain much from teaching the material. What really is great and enjoyable is that every semester there is a new group of kids that come in that don’t really know what you know and want to.
You get a group of 30 kids and you make life-long friends out of them, some of them turn out to be graduate students. That’s the part that’s fun and rewarding. So, I try to have a lot of dialogue in my classes and ask questions and entertain questions so they’re participating, it’s not just lectures.
Q: What are you focused on today?
A: One [shorter-term project] is based on narrow linewidth lasers. The spectral purity of a laser depends on a lot of things. Consider, for example, an FM radio. The reason that you can have adjacent stations is that the energy they are transmitting falls in a narrow enough band that they don’t overlap. The same thing applies to the laser. The laser is electromagnetic radiation, just like a radio wave. So making semiconductor lasers that are very narrow allows you to use them for certain applications that are important, one of which is spectroscopy. You can use them to sample whether or not certain atoms are present or how many [are present]. You can use that for applications in homeland security, to study the molecular structure or molecular gas content in the upper atmosphere for environmental or weather purposes, you can use it in laboratories, in manufacturing environments, and so on. So there is a lot of interest in having a tiny little laser like the ones that are in a CD player or laser pointer, but that can be used to do this chemical analysis kind of thing. So we’ve been working on that. We have some unique structures that give us these very narrow line widths and allow us to do some things that you can’t do with otherwise conventional lasers.
[A longer-term project] is what’s called quantum dots…laser devices that have embedded in them small enough chunks of material that quantum mechanics plays a very strong role in how they behave and there is a lot of basic physics and materials science that goes into this. It’s difficult to make them which is part of the reason it’s a long term project. There is a driving need for electronic devices and optical devices that do things that are much smaller and so we’re in the middle of that. And what that leads to ultimately is very low power devices that are physically small, electrically fast, optically fast, and lead to greater density of devices and more integration and more computational power and more communications power and things like that. The whole world is always interested in faster, smaller, cheaper.
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